Method and apparatus for reporting logging information in wireless communication system

ABSTRACT

The present disclosure relates to reporting logging information in wireless communications. According to an embodiment of the present disclosure, the wireless device may report information informing that an out-of-coverage is detected upon a subscriber identity module (SIM) switching, to a network.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 119 (a), this application claims the benefit ofKorean Patent Application No. 10-2020-0167640 filed on Dec. 3, 2020, thecontents of which are all hereby incorporated by reference herein intheir entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to reporting logging information inwireless communications.

Related Art

3rd generation partnership project (3GPP) long-term evolution (LTE) is atechnology for enabling high-speed packet communications. Many schemeshave been proposed for the LTE objective including those that aim toreduce user and provider costs, improve service quality, and expand andimprove coverage and system capacity. The 3GPP LTE requires reduced costper bit, increased service availability, flexible use of a frequencyband, a simple structure, an open interface, and adequate powerconsumption of a terminal as an upper-level requirement.

Work has started in international telecommunication union (ITU) and 3GPPto develop requirements and specifications for new radio (NR) systems.3GPP has to identify and develop the technology components needed forsuccessfully standardizing the new RAT timely satisfying both the urgentmarket needs, and the more long-term requirements set forth by the ITUradio communication sector (ITU-R) international mobiletelecommunications (IMT)-2020 process. Further, the NR should be able touse any spectrum band ranging at least up to 100 GHz that may be madeavailable for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usagescenarios, requirements and deployment scenarios including enhancedmobile broadband (eMBB), massive machine-type-communications (mMTC),ultra-reliable and low latency communications (URLLC), etc. The NR shallbe inherently forward compatible.

In wireless communications, there may be a need to perform a drivingtest to measure a network coverage for coverage optimization. Theminimization of driving test (MDT) may refer to a test by operators formeasuring the network coverage using a UE instead of a vehicle. For theMDT, the UE may generate logging information and report the logginginformation to a network.

SUMMARY OF THE DISCLOSURE Technical Problem

An aspect of the present disclosure is to provide method and apparatusfor reporting logging information in a wireless communication system.

Another aspect of the present disclosure is to provide method andapparatus for generating logging information in a wireless communicationsystem.

Yet another aspect of the present disclosure is to provide method andapparatus for generating and reporting logging information in a MUSIMoperation in a wireless communication system.

Technical Solution

According to an embodiment of the present disclosure, a method performedby a wireless device in a wireless communication system comprises:registering to a first network and a second network; receiving a logginginstruction for out-of-service; detecting an out-of-service coverageupon switching to the first network from the second network; generatinglogging information for the detected out-of-service coverage based onthe logging instruction for out-of-service, wherein the logginginformation comprises information informing that the out-of-servicecoverage is detected upon switching to the first network from the secondnetwork; and transmitting the logging information.

According to an embodiment of the present disclosure, a wireless devicein a wireless communication system comprises: a transceiver; a memory;and at least one processor operatively coupled to the transceiver andthe memory, and configured to: register to a first network and a secondnetwork; control the transceiver to receive a logging instruction forout-of-service; detect an out-of-service coverage upon switching to thefirst network from the second network; generate logging information forthe detected out-of-service coverage based on the logging instructionfor out-of-service, wherein the logging information comprisesinformation informing that the out-of-service coverage is detected uponswitching to the first network from the second network; and control thetransceiver to transmit the logging information.

According to an embodiment of the present disclosure, a non-transitorycomputer-readable medium has stored thereon a plurality of instructions.The plurality of instructions, when executed by a processor of awireless device, cause the wireless device to: register to a firstnetwork and a second network; receive a logging instruction forout-of-service; detect an out-of-service coverage upon switching to thefirst network from the second network; generate logging information forthe detected out-of-service coverage based on the logging instructionfor out-of-service, wherein the logging information comprisesinformation informing that the out-of-service coverage is detected uponswitching to the first network from the second network; and transmit thelogging information.

Advantageous Effect

The present disclosure can have various advantageous effects.

For example, when the network provides a configuration to perform alogged measurement to the UE which is capable to support MUSIMoperation, in addition to the logged measurement result, the UE canprovide an indication that the out-of-service coverage has been enteredbefore switching MUSIM operation in a logged measurement report so thatthe network can assume that the actual size/area of the out-of-servicecoverage is bigger than the reported size/area. Therefore, the networkcan prevent misinterpretation of the size/area of the out-of-servicecoverage by the indication in the logged measurement report.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied.

FIG. 2 shows an example of a wireless communication system to which thetechnical features of the present disclosure can be applied.

FIG. 3 shows an example of a wireless communication system to which thetechnical features of the present disclosure can be applied.

FIG. 4 shows another example of a wireless communication system to whichthe technical features of the present disclosure can be applied.

FIG. 5 shows a block diagram of a user plane protocol stack to which thetechnical features of the present disclosure can be applied.

FIG. 6 shows a block diagram of a control plane protocol stack to whichthe technical features of the present disclosure can be applied.

FIG. 7 illustrates a frame structure in a 3GPP based wirelesscommunication system.

FIG. 8 illustrates a data flow example in the 3GPP NR system.

FIG. 9 shows an example of possible RRC states in a wirelesscommunication system to which technical features of the presentdisclosure can be applied.

FIG. 10 shows an example of a process for performing an MDT to whichtechnical features of the present disclosure can be applied.

FIG. 11 shows an example of a wireless environment in which a MUSIMdevice operates according to an embodiment of the present disclosure.

FIG. 12 shows an example of a method performed by a wireless deviceaccording to an embodiment of the present disclosure.

FIG. 13 shows an example of a method performed by a base station (BS) ina first network according to an embodiment of the present disclosure.

FIG. 14 shows an example of a method for logging out-of-service coverageinformation during MUSIM operation according to an embodiment of thepresent disclosure.

FIG. 15 shows a UE to implement an embodiment of the present disclosure.

FIG. 16 shows another example of a wireless communication system towhich the technical features of the present disclosure can be applied.

FIG. 17 shows an example of an AI device to which the technical featuresof the present disclosure can be applied.

FIG. 18 shows an example of an AI system to which the technical featuresof the present disclosure can be applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technical features described below may be used by a communicationstandard by the 3rd generation partnership project (3GPP)standardization organization, a communication standard by the instituteof electrical and electronics engineers (IEEE), etc. For example, thecommunication standards by the 3GPP standardization organization includelong-term evolution (LTE) and/or evolution of LTE systems. The evolutionof LTE systems includes LTE-advanced (LTE-A), LTE-A Pro, and/or 5G newradio (NR). The communication standard by the IEEE standardizationorganization includes a wireless local area network (WLAN) system suchas IEEE 802.11a/b/g/n/ac/ax. The above system uses various multipleaccess technologies such as orthogonal frequency division multipleaccess (OFDMA) and/or single carrier frequency division multiple access(SC-FDMA) for downlink (DL) and/or uplink (UL). For example, only OFDMAmay be used for DL and only SC-FDMA may be used for UL. Alternatively,OFDMA and SC-FDMA may be used for DL and/or UL.

In the present disclosure, “A or B” may mean “only A”, “only B”, or“both A and B”. In other words, “A or B” in the present disclosure maybe interpreted as “A and/or B”. For example, “A, B or C” in the presentdisclosure may mean “only A”, “only B”, “only C”, or “any combination ofA, B and C”.

In the present disclosure, slash (/) or comma (,) may mean “and/or”. Forexample, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “onlyA”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, Bor C”.

In the present disclosure, “at least one of A and B” may mean “only A”,“only B” or “both A and B”. In addition, the expression “at least one ofA or B” or “at least one of A and/or B” in the present disclosure may beinterpreted as same as “at least one of A and B”.

In addition, in the present disclosure, “at least one of A, B and C” maymean “only A”, “only B”, “only C”, or “any combination of A, B and C”.In addition, “at least one of A, B or C” or “at least one of A, B and/orC” may mean “at least one of A, B and C”.

Also, parentheses used in the present disclosure may mean “for example”.In detail, when it is shown as “control information (PDCCH)”, “PDCCH”may be proposed as an example of “control information”. In other words,“control information” in the present disclosure is not limited to“PDCCH”, and “PDDCH” may be proposed as an example of “controlinformation”. In addition, even when shown as “control information(i.e., PDCCH)”, “PDCCH” may be proposed as an example of “controlinformation”.

Technical features that are separately described in one drawing in thepresent disclosure may be implemented separately or simultaneously.

Throughout the disclosure, the terms ‘radio access network (RAN) node’,‘base station’, ‘eNB’, ‘gNB’ and ‘cell’ may be used interchangeably.Further, a UE may be a kind of a wireless device, and throughout thedisclosure, the terms ‘UE’ and ‘wireless device’ may be usedinterchangeably.

Throughout the disclosure, the terms ‘cell quality’, ‘signal strength’,‘signal quality’, ‘channel state’, ‘channel quality’, ‘ channelstate/reference signal received power (RSRP)’ and ‘ reference signalreceived quality (RSRQ)’ may be used interchangeably.

The following drawings are created to explain specific embodiments ofthe present disclosure. The names of the specific devices or the namesof the specific signals/messages/fields shown in the drawings areprovided by way of example, and thus the technical features of thepresent disclosure are not limited to the specific names used in thefollowing drawings.

FIG. 1 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied.

The 5G usage scenarios shown in FIG. 1 are only exemplary, and thetechnical features of the present disclosure can be applied to other 5Gusage scenarios which are not shown in FIG. 1 .

Referring to FIG. 1 , the three main requirements areas of 5G include(1) enhanced mobile broadband (eMBB) domain, (2) massive machine typecommunication (mMTC) area, and (3) ultra-reliable and low latencycommunications (URLLC) area. Some use cases may require multiple areasfor optimization and, other use cases may only focus on only one keyperformance indicator (KPI). 5G is to support these various use cases ina flexible and reliable way.

eMBB focuses on across-the-board enhancements to the data rate, latency,user density, capacity and coverage of mobile broadband access. The eMBBaims ˜10 Gbps of throughput. eMBB far surpasses basic mobile Internetaccess and covers rich interactive work and media and entertainmentapplications in cloud and/or augmented reality. Data is one of the keydrivers of 5G and may not be able to see dedicated voice services forthe first time in the 5G era. In 5G, the voice is expected to beprocessed as an application simply using the data connection provided bythe communication system. The main reason for the increased volume oftraffic is an increase in the size of the content and an increase in thenumber of applications requiring high data rates. Streaming services(audio and video), interactive video and mobile Internet connectivitywill become more common as more devices connect to the Internet. Many ofthese applications require always-on connectivity to push real-timeinformation and notifications to the user. Cloud storage andapplications are growing rapidly in mobile communication platforms,which can be applied to both work and entertainment. Cloud storage is aspecial use case that drives growth of uplink data rate. 5G is also usedfor remote tasks on the cloud and requires much lower end-to-end delayto maintain a good user experience when the tactile interface is used.In entertainment, for example, cloud games and video streaming areanother key factor that increases the demand for mobile broadbandcapabilities. Entertainment is essential in smartphones and tabletsanywhere, including high mobility environments such as trains, cars andairplanes. Another use case is augmented reality and informationretrieval for entertainment. Here, augmented reality requires very lowlatency and instantaneous data amount.

mMTC is designed to enable communication between devices that arelow-cost, massive in number and battery-driven, intended to supportapplications such as smart metering, logistics, and field and bodysensors. mMTC aims ˜10 years on battery and/or ˜1 million devices/km2.mMTC allows seamless integration of embedded sensors in all areas and isone of the most widely used 5G applications. Potentially by 2020,internet-of-things (IoT) devices are expected to reach 20.4 billion.Industrial IoT is one of the areas where 5G plays a key role in enablingsmart cities, asset tracking, smart utilities, agriculture and securityinfrastructures.

URLLC will make it possible for devices and machines to communicate withultra-reliability, very low latency and high availability, making itideal for vehicular communication, industrial control, factoryautomation, remote surgery, smart grids and public safety applications.URLLC aims ˜1 ms of latency. URLLC includes new services that willchange the industry through links with ultra-reliability/low latency,such as remote control of key infrastructure and self-driving vehicles.The level of reliability and latency is essential for smart gridcontrol, industrial automation, robotics, drones control andcoordination.

Next, a plurality of use cases included in the triangle of FIG. 1 willbe described in more detail.

5G can complement fiber-to-the-home (FTTH) and cable-based broadband (orDOCSIS) as a means of delivering streams rated from hundreds of megabitsper second to gigabits per second. This high speed can be required todeliver TVs with resolutions of 4K or more (6K, 8K and above) as well asvirtual reality (VR) and augmented reality (AR). VR and AR applicationsinclude mostly immersive sporting events. Certain applications mayrequire special network settings. For example, in the case of a VR game,a game company may need to integrate a core server with an edge networkserver of a network operator to minimize delay.

Automotive is expected to become an important new driver for 5G, withmany use cases for mobile communications to vehicles. For example,entertainment for passengers demands high capacity and high mobilebroadband at the same time. This is because future users will continueto expect high-quality connections regardless of their location andspeed. Another use case in the automotive sector is an augmented realitydashboard. The driver can identify an object in the dark on top of whatis being viewed through the front window through the augmented realitydashboard. The augmented reality dashboard displays information thatwill inform the driver about the object's distance and movement. In thefuture, the wireless module enables communication between vehicles,information exchange between the vehicle and the supportinginfrastructure, and information exchange between the vehicle and otherconnected devices (e.g. devices accompanied by a pedestrian). The safetysystem allows the driver to guide the alternative course of action sothat he can drive more safely, thereby reducing the risk of accidents.The next step will be a remotely controlled vehicle or self-drivingvehicle. This requires a very reliable and very fast communicationbetween different self-driving vehicles and between vehicles andinfrastructure. In the future, a self-driving vehicle will perform alldriving activities, and the driver will focus only on traffic that thevehicle itself cannot identify. The technical requirements ofself-driving vehicles require ultra-low latency and high-speedreliability to increase traffic safety to a level not achievable byhumans.

Smart cities and smart homes, which are referred to as smart societies,will be embedded in high density wireless sensor networks. Thedistributed network of intelligent sensors will identify conditions forcost and energy-efficient maintenance of a city or house. A similarsetting can be performed for each home. Temperature sensors, windows andheating controllers, burglar alarms and appliances are all wirelesslyconnected. Many of these sensors typically require low data rate, lowpower and low cost. However, for example, real-time high-definition (HD)video may be required for certain types of devices for monitoring.

The consumption and distribution of energy, including heat or gas, ishighly dispersed, requiring automated control of distributed sensornetworks. The smart grid interconnects these sensors using digitalinformation and communication technologies to collect and act oninformation. This information can include supplier and consumerbehavior, allowing the smart grid to improve the distribution of fuel,such as electricity, in terms of efficiency, reliability, economy,production sustainability, and automated methods. The smart grid can beviewed as another sensor network with low latency.

The health sector has many applications that can benefit from mobilecommunications. Communication systems can support telemedicine toprovide clinical care in remote locations. This can help to reducebarriers to distance and improve access to health services that are notcontinuously available in distant rural areas. It is also used to savelives in critical care and emergency situations. Mobile communicationbased wireless sensor networks can provide remote monitoring and sensorsfor parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantin industrial applications. Wiring costs are high for installation andmaintenance. Thus, the possibility of replacing a cable with a wirelesslink that can be reconfigured is an attractive opportunity in manyindustries. However, achieving this requires that wireless connectionsoperate with similar delay, reliability, and capacity as cables and thattheir management is simplified. Low latency and very low errorprobabilities are new requirements that need to be connected to 5G.

Logistics and freight tracking are important use cases of mobilecommunications that enable tracking of inventory and packages anywhereusing location based information systems. Use cases of logistics andfreight tracking typically require low data rates, but require a largerange and reliable location information.

NR supports multiple numerology (or, subcarrier spacing (SCS)) tosupport various 5G services. For example, when the SCS is 15 kHz, widearea in traditional cellular bands may be supported. When the SCS is 30kHz/60 kHz, dense-urban, lower latency and wider carrier bandwidth maybe supported. When the SCS is 60 kHz or higher, a bandwidth greater than24.25 GHz may be supported to overcome phase noise.

The NR frequency band may be defined as two types of frequency range,i.e., FR1 and FR2. The numerical value of the frequency range may bechanged. For example, the frequency ranges of the two types (FR1 andFR2) may be as shown in Table 1 below. For ease of explanation, in thefrequency ranges used in the NR system, FR1 may mean “sub 6 GHz range”,FR2 may mean “above 6 GHz range,” and may be referred to as millimeterwave (mmW).

TABLE 1 Frequency Range Corresponding frequency designation rangeSubcarrier Spacing FR1  450 MHz-6000 MHz 15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

As mentioned above, the numerical value of the frequency range of the NRsystem may be changed. For example, FR1 may include a frequency band of410 MHz to 7125 MHz as shown in Table 2 below. That is, FR1 may includea frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more. Forexample, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) ormore included in FR1 may include an unlicensed band. Unlicensed bandsmay be used for a variety of purposes, for example for communication forvehicles (e.g., autonomous driving).

TABLE 2 Frequency Range Corresponding frequency designation rangeSubcarrier Spacing FR1  410 MHz-7125 MHz 15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

FIG. 2 shows an example of a wireless communication system to which thetechnical features of the present disclosure can be applied.

Referring to FIG. 2 , the wireless communication system may include afirst device 210 and a second device 220.

The first device 210 includes a base station, a network node, atransmitting UE, a receiving UE, a wireless device, a wirelesscommunication device, a vehicle, a vehicle equipped with an autonomousdriving function, a connected car, a drone, an unmanned aerial vehicle(UAV), an artificial intelligence (AI) module, a robot, an AR device, aVR device, a mixed reality (MR) device, a hologram device, a publicsafety device, an MTC device, an IoT device, a medical device, afin-tech device (or, a financial device), a security device, aclimate/environmental device, a device related to 5G services, or adevice related to the fourth industrial revolution.

The second device 220 includes a base station, a network node, atransmitting UE, a receiving UE, a wireless device, a wirelesscommunication device, a vehicle, a vehicle equipped with an autonomousdriving function, a connected car, a drone, a UAV, an AI module, arobot, an AR device, a VR device, an MR device, a hologram device, apublic safety device, an MTC device, an IoT device, a medical device, afin-tech device (or, a financial device), a security device, aclimate/environmental device, a device related to 5G services, or adevice related to the fourth industrial revolution.

For example, the UE may include a mobile phone, a smart phone, a laptopcomputer, a digital broadcasting terminal, a personal digital assistant(PDA), a portable multimedia player (PMP), a navigation device, a slatepersonal computer (PC), a tablet PC, an ultrabook, a wearable device(e.g. a smartwatch, a smart glass, a head mounted display (HMD)). Forexample, the HMD may be a display device worn on the head. For example,the HMD may be used to implement AR, VR and/or MR.

For example, the drone may be a flying object that is flying by a radiocontrol signal without a person boarding it. For example, the VR devicemay include a device that implements an object or background in thevirtual world. For example, the AR device may include a device thatimplements connection of an object and/or a background of a virtualworld to an object and/or a background of the real world. For example,the MR device may include a device that implements fusion of an objectand/or a background of a virtual world to an object and/or a backgroundof the real world. For example, the hologram device may include a devicethat implements a 360-degree stereoscopic image by recording and playingstereoscopic information by utilizing a phenomenon of interference oflight generated by the two laser lights meeting with each other, calledholography. For example, the public safety device may include a videorelay device or a video device that can be worn by the user's body. Forexample, the MTC device and the IoT device may be a device that do notrequire direct human intervention or manipulation. For example, the MTCdevice and the IoT device may include a smart meter, a vending machine,a thermometer, a smart bulb, a door lock and/or various sensors. Forexample, the medical device may be a device used for the purpose ofdiagnosing, treating, alleviating, handling, or preventing a disease.For example, the medical device may be a device used for the purpose ofdiagnosing, treating, alleviating, or correcting an injury or disorder.For example, the medical device may be a device used for the purpose ofinspecting, replacing or modifying a structure or function. For example,the medical device may be a device used for the purpose of controllingpregnancy. For example, the medical device may include a treatmentdevice, a surgical device, an (in vitro) diagnostic device, a hearingaid and/or a procedural device, etc. For example, a security device maybe a device installed to prevent the risk that may occur and to maintainsafety. For example, the security device may include a camera, aclosed-circuit TV (CCTV), a recorder, or a black box. For example, thefin-tech device may be a device capable of providing financial servicessuch as mobile payment. For example, the fin-tech device may include apayment device or a point of sales (POS). For example, theclimate/environmental device may include a device for monitoring orpredicting the climate/environment.

The first device 210 may include at least one or more processors, suchas a processor 211, at least one memory, such as a memory 212, and atleast one transceiver, such as a transceiver 213. The processor 211 mayperform the functions, procedures, and/or methods of the first devicedescribed throughout the disclosure. The processor 211 may perform oneor more protocols. For example, the processor 211 may perform one ormore layers of the air interface protocol. The memory 212 is connectedto the processor 211 and may store various types of information and/orinstructions. The transceiver 213 is connected to the processor 211 andmay be controlled by the processor 211 to transmit and receive wirelesssignals.

The second device 220 may include at least one or more processors, suchas a processor 221, at least one memory, such as a memory 222, and atleast one transceiver, such as a transceiver 223. The processor 221 mayperform the functions, procedures, and/or methods of the second device220 described throughout the disclosure. The processor 221 may performone or more protocols. For example, the processor 221 may perform one ormore layers of the air interface protocol. The memory 222 is connectedto the processor 221 and may store various types of information and/orinstructions. The transceiver 223 is connected to the processor 221 andmay be controlled by the processor 221 to transmit and receive wirelesssignals.

The memory 212, 222 may be connected internally or externally to theprocessor 211, 212, or may be connected to other processors via avariety of technologies such as wired or wireless connections.

The first device 210 and/or the second device 220 may have more than oneantenna. For example, antenna 214 and/or antenna 224 may be configuredto transmit and receive wireless signals.

FIG. 3 shows an example of a wireless communication system to which thetechnical features of the present disclosure can be applied.

Specifically, FIG. 3 shows a system architecture based on anevolved-UMTS terrestrial radio access network (E-UTRAN). Theaforementioned LTE is a part of an evolved-UTMS (e-UMTS) using theE-UTRAN.

Referring to FIG. 3 , the wireless communication system includes one ormore user equipment (UE) 310, an E-UTRAN and an evolved packet core(EPC). The UE 310 refers to a communication equipment carried by a user.The UE 310 may be fixed or mobile. The UE 310 may be referred to asanother terminology, such as a mobile station (MS), a user terminal(UT), a subscriber station (SS), a wireless device, etc.

The E-UTRAN consists of one or more evolved NodeB (eNB) 320. The eNB 320provides the E-UTRA user plane and control plane protocol terminationstowards the UE 10. The eNB 320 is generally a fixed station thatcommunicates with the UE 310. The eNB 320 hosts the functions, such asinter-cell radio resource management (RRM), radio bearer (RB) control,connection mobility control, radio admission control, measurementconfiguration/provision, dynamic resource allocation (scheduler), etc.The eNB 320 may be referred to as another terminology, such as a basestation (BS), a base transceiver system (BTS), an access point (AP),etc.

A downlink (DL) denotes communication from the eNB 320 to the UE 310. Anuplink (UL) denotes communication from the UE 310 to the eNB 320. Asidelink (SL) denotes communication between the UEs 310. In the DL, atransmitter may be a part of the eNB 320, and a receiver may be a partof the UE 310. In the UL, the transmitter may be a part of the UE 310,and the receiver may be a part of the eNB 320. In the SL, thetransmitter and receiver may be a part of the UE 310.

The EPC includes a mobility management entity (MME), a serving gateway(S-GW) and a packet data network (PDN) gateway (P-GW). The MME hosts thefunctions, such as non-access stratum (NAS) security, idle statemobility handling, evolved packet system (EPS) bearer control, etc. TheS-GW hosts the functions, such as mobility anchoring, etc. The S-GW is agateway having an E-UTRAN as an endpoint. For convenience, MME/S-GW 330will be referred to herein simply as a “gateway,” but it is understoodthat this entity includes both the MME and S-GW. The P-GW hosts thefunctions, such as UE Internet protocol (IP) address allocation, packetfiltering, etc. The P-GW is a gateway having a PDN as an endpoint. TheP-GW is connected to an external network.

The UE 310 is connected to the eNB 320 by means of the Uu interface. TheUEs 310 are interconnected with each other by means of the PC5interface. The eNBs 320 are interconnected with each other by means ofthe X2 interface. The eNBs 320 are also connected by means of the S1interface to the EPC, more specifically to the MME by means of theS1-MME interface and to the S-GW by means of the S1-U interface. The S1interface supports a many-to-many relation between MMEs/S-GWs and eNBs.

FIG. 4 shows another example of a wireless communication system to whichthe technical features of the present disclosure can be applied.

Specifically, FIG. 4 shows a system architecture based on a 5G NR. Theentity used in the 5G NR (hereinafter, simply referred to as “NW”) mayabsorb some or all of the functions of the entities introduced in FIG. 3(e.g. eNB, MME, S-GW). The entity used in the NR may be identified bythe name “NG” for distinction from the LTE/LTE-A.

Referring to FIG. 4 , the wireless communication system includes one ormore UE 410, a next-generation RAN (NG-RAN) and a 5th generation corenetwork (5GC). The NG-RAN consists of at least one NG-RAN node. TheNG-RAN node is an entity corresponding to the eNB 320 shown in FIG. 3 .The NG-RAN node consists of at least one gNB 421 and/or at least oneng-eNB 422. The gNB 421 provides NR user plane and control planeprotocol terminations towards the UE 410. The ng-eNB 422 provides E-UTRAuser plane and control plane protocol terminations towards the UE 410.

The 5GC includes an access and mobility management function (AMF), auser plane function (UPF) and a session management function (SMF). TheAMF hosts the functions, such as NAS security, idle state mobilityhandling, etc. The AMF is an entity including the functions of theconventional MME. The UPF hosts the functions, such as mobilityanchoring, protocol data unit (PDU) handling. The UPF an entityincluding the functions of the conventional S-GW. The SMF hosts thefunctions, such as UE IP address allocation, PDU session control.

The gNBs 421 and ng-eNBs 422 are interconnected with each other by meansof the Xn interface. The gNBs 421 and ng-eNBs 422 are also connected bymeans of the NG interfaces to the 5GC, more specifically to the AMF bymeans of the NG-C interface and to the UPF by means of the NG-Uinterface.

A protocol structure between network entities described above isdescribed. On the system of FIG. 3 and/or FIG. 4 , layers of a radiointerface protocol between the UE and the network (e.g. NG-RAN and/orE-UTRAN) may be classified into a first layer (L1), a second layer (L2),and a third layer (L3) based on the lower three layers of the opensystem interconnection (OSI) model that is well-known in thecommunication system.

FIG. 5 shows a block diagram of a user plane protocol stack to which thetechnical features of the present disclosure can be applied. FIG. 6shows a block diagram of a control plane protocol stack to which thetechnical features of the present disclosure can be applied.

The user/control plane protocol stacks shown in FIG. 5 and FIG. 6 areused in NR. However, user/control plane protocol stacks shown in FIG. 5and FIG. 6 may be used in LTE/LTE-A without loss of generality, byreplacing gNB/AMF with eNB/MME.

Referring to FIG. 5 and FIG. 6 , a physical (PHY) layer belonging to L1.The PHY layer offers information transfer services to media accesscontrol (MAC) sublayer and higher layers. The PHY layer offers to theMAC sublayer transport channels. Data between the MAC sublayer and thePHY layer is transferred via the transport channels. Between differentPHY layers, i.e., between a PHY layer of a transmission side and a PHYlayer of a reception side, data is transferred via the physicalchannels.

The MAC sublayer belongs to L2. The main services and functions of theMAC sublayer include mapping between logical channels and transportchannels, multiplexing/de-multiplexing of MAC service data units (SDUs)belonging to one or different logical channels into/from transportblocks (TB) delivered to/from the physical layer on transport channels,scheduling information reporting, error correction through hybridautomatic repeat request (HARQ), priority handling between UEs by meansof dynamic scheduling, priority handling between logical channels of oneUE by means of logical channel prioritization (LCP), etc. The MACsublayer offers to the radio link control (RLC) sublayer logicalchannels.

The RLC sublayer belong to L2. The RLC sublayer supports threetransmission modes, i.e. transparent mode (TM), unacknowledged mode(UM), and acknowledged mode (AM), in order to guarantee various qualityof services (QoS) required by radio bearers. The main services andfunctions of the RLC sublayer depend on the transmission mode. Forexample, the RLC sublayer provides transfer of upper layer PDUs for allthree modes, but provides error correction through ARQ for AM only. InLTE/LTE-A, the RLC sublayer provides concatenation, segmentation andreassembly of RLC SDUs (only for UM and AM data transfer) andre-segmentation of RLC data PDUs (only for AM data transfer). In NR, theRLC sublayer provides segmentation (only for AM and UM) andre-segmentation (only for AM) of RLC SDUs and reassembly of SDU (onlyfor AM and UM). That is, the NR does not support concatenation of RLCSDUs. The RLC sublayer offers to the packet data convergence protocol(PDCP) sublayer RLC channels.

The PDCP sublayer belong to L2. The main services and functions of thePDCP sublayer for the user plane include header compression anddecompression, transfer of user data, duplicate detection, PDCP PDUrouting, retransmission of PDCP SDUs, ciphering and deciphering, etc.The main services and functions of the PDCP sublayer for the controlplane include ciphering and integrity protection, transfer of controlplane data, etc.

The service data adaptation protocol (SDAP) sublayer belong to L2. TheSDAP sublayer is only defined in the user plane. The SDAP sublayer isonly defined for NR. The main services and functions of SDAP include,mapping between a QoS flow and a data radio bearer (DRB), and markingQoS flow ID (QFI) in both DL and UL packets. The SDAP sublayer offers to5GC QoS flows.

A radio resource control (RRC) layer belongs to L3. The RRC layer isonly defined in the control plane. The RRC layer controls radioresources between the UE and the network. To this end, the RRC layerexchanges RRC messages between the UE and the BS. The main services andfunctions of the RRC layer include broadcast of system informationrelated to AS and NAS, paging, establishment, maintenance and release ofan RRC connection between the UE and the network, security functionsincluding key management, establishment, configuration, maintenance andrelease of radio bearers, mobility functions, QoS management functions,UE measurement reporting and control of the reporting, NAS messagetransfer to/from NAS from/to UE.

In other words, the RRC layer controls logical channels, transportchannels, and physical channels in relation to the configuration,reconfiguration, and release of radio bearers. A radio bearer refers toa logical path provided by L1 (PHY layer) and L2 (MAC/RLC/PDCP/SDAPsublayer) for data transmission between a UE and a network. Setting theradio bearer means defining the characteristics of the radio protocollayer and the channel for providing a specific service, and setting eachspecific parameter and operation method. Radio bearer may be dividedinto signaling RB (SRB) and data RB (DRB). The SRB is used as a path fortransmitting RRC messages in the control plane, and the DRB is used as apath for transmitting user data in the user plane.

An RRC state indicates whether an RRC layer of the UE is logicallyconnected to an RRC layer of the E-UTRAN. In LTE/LTE-A, when the RRCconnection is established between the RRC layer of the UE and the RRClayer of the E-UTRAN, the UE is in the RRC connected state(RRC_CONNECTED). Otherwise, the UE is in the RRC idle state (RRC_IDLE).In NR, the RRC inactive state (RRC_INACTIVE) is additionally introduced.RRC_INACTIVE may be used for various purposes. For example, the massivemachine type communications (MMTC) UEs can be efficiently managed inRRC_INACTIVE. When a specific condition is satisfied, transition is madefrom one of the above three states to the other.

A predetermined operation may be performed according to the RRC state.In RRC_IDLE, public land mobile network (PLMN) selection, broadcast ofsystem information (SI), cell re-selection mobility, core network (CN)paging and discontinuous reception (DRX) configured by NAS may beperformed. The UE shall have been allocated an identifier (ID) whichuniquely identifies the UE in a tracking area. No RRC context stored inthe BS.

In RRC_CONNECTED, the UE has an RRC connection with the network (i.e.E-UTRAN/NG-RAN). Network-CN connection (both C/U-planes) is alsoestablished for UE. The UE AS context is stored in the network and theUE. The RAN knows the cell which the UE belongs to. The network cantransmit and/or receive data to/from UE. Network controlled mobilityincluding measurement is also performed.

Most of operations performed in RRC_IDLE may be performed inRRC_INACTIVE. But, instead of CN paging in RRC_IDLE, RAN paging isperformed in RRC_INACTIVE. In other words, in RRC_IDLE, paging formobile terminated (MT) data is initiated by core network and paging areais managed by core network. In RRC_INACTIVE, paging is initiated byNG-RAN, and RAN-based notification area (RNA) is managed by NG-RAN.Further, instead of DRX for CN paging configured by NAS in RRC_IDLE, DRXfor RAN paging is configured by NG-RAN in RRC_INACTIVE. Meanwhile, inRRC_INACTIVE, 5GC-NG-RAN connection (both C/U-planes) is established forUE, and the UE AS context is stored in NG-RAN and the UE. NG-RAN knowsthe RNA which the UE belongs to.

NAS layer is located at the top of the RRC layer. The NAS controlprotocol performs the functions, such as authentication, mobilitymanagement, security control.

The physical channels may be modulated according to OFDM processing andutilizes time and frequency as radio resources. The physical channelsconsist of a plurality of orthogonal frequency division multiplexing(OFDM) symbols in time domain and a plurality of subcarriers infrequency domain. One subframe consists of a plurality of OFDM symbolsin the time domain. A resource block is a resource allocation unit, andconsists of a plurality of OFDM symbols and a plurality of subcarriers.In addition, each subframe may use specific subcarriers of specific OFDMsymbols (e.g. first OFDM symbol) of the corresponding subframe for aphysical downlink control channel (PDCCH), i.e. L1/L2 control channel. Atransmission time interval (TTI) is a basic unit of time used by ascheduler for resource allocation. The TTI may be defined in units ofone or a plurality of slots, or may be defined in units of mini-slots.

The transport channels are classified according to how and with whatcharacteristics data are transferred over the radio interface. DLtransport channels include a broadcast channel (BCH) used fortransmitting system information, a downlink shared channel (DL-SCH) usedfor transmitting user traffic or control signals, and a paging channel(PCH) used for paging a UE. UL transport channels include an uplinkshared channel (UL-SCH) for transmitting user traffic or control signalsand a random access channel (RACH) normally used for initial access to acell.

Different kinds of data transfer services are offered by MAC sublayer.Each logical channel type is defined by what type of information istransferred. Logical channels are classified into two groups: controlchannels and traffic channels.

Control channels are used for the transfer of control plane informationonly. The control channels include a broadcast control channel (BCCH), apaging control channel (PCCH), a common control channel (CCCH) and adedicated control channel (DCCH). The BCCH is a DL channel forbroadcasting system control information. The PCCH is DL channel thattransfers paging information, system information change notifications.The CCCH is a channel for transmitting control information between UEsand network. This channel is used for UEs having no RRC connection withthe network. The DCCH is a point-to-point bi-directional channel thattransmits dedicated control information between a UE and the network.This channel is used by UEs having an RRC connection.

Traffic channels are used for the transfer of user plane informationonly. The traffic channels include a dedicated traffic channel (DTCH).The DTCH is a point-to-point channel, dedicated to one UE, for thetransfer of user information. The DTCH can exist in both UL and DL.

Regarding mapping between the logical channels and transport channels,in DL, BCCH can be mapped to BCH, BCCH can be mapped to DL-SCH, PCCH canbe mapped to PCH, CCCH can be mapped to DL-SCH, DCCH can be mapped toDL-SCH, and DTCH can be mapped to DL-SCH. In UL, CCCH can be mapped toUL-SCH, DCCH can be mapped to UL-SCH, and DTCH can be mapped to UL-SCH.

FIG. 7 illustrates a frame structure in a 3GPP based wirelesscommunication system.

The frame structure illustrated in FIG. 7 is purely exemplary and thenumber of subframes, the number of slots, and/or the number of symbolsin a frame may be variously changed. In the 3GPP based wirelesscommunication system, an OFDM numerology (e.g., subcarrier spacing(SCS), transmission time interval (TTI) duration) may be differentlyconfigured between a plurality of cells aggregated for one UE. Forexample, if a UE is configured with different SCSs for cells aggregatedfor the cell, an (absolute time) duration of a time resource (e.g. asubframe, a slot, or a TTI) including the same number of symbols may bedifferent among the aggregated cells. Herein, symbols may include OFDMsymbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fouriertransform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to FIG. 7 , downlink and uplink transmissions are organizedinto frames. Each frame has Tf=10 ms duration. Each frame is dividedinto two half-frames, where each of the half-frames has 5 ms duration.Each half-frame consists of 5 subframes, where the duration Tsf persubframe is 1 ms. Each subframe is divided into slots and the number ofslots in a subframe depends on a subcarrier spacing. Each slot includes14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP,each slot includes 14 OFDM symbols and, in an extended CP, each slotincludes 12 OFDM symbols. The numerology is based on exponentiallyscalable subcarrier spacing Δf=2u*15 kHz. The following table shows thenumber of OFDM symbols per slot, the number of slots per frame, and thenumber of slots per for the normal CP, according to the subcarrierspacing Δf=2u*15 kHz.

TABLE 3 u Nslotsymb Nframe,uslot Nsubframe,uslot 0 14 10 1 1 14 20 2 214 40 4 3 14 80 8 4 14 160 16

The following table shows the number of OFDM symbols per slot, thenumber of slots per frame, and the number of slots per for the extendedCP, according to the subcarrier spacing Δf=2u*15 kHz.

TABLE 4 u Nslotsymb Nframe,uslot Nsubframe,uslot 2 12 40 4

A slot includes plural symbols (e.g., 14 or 12 symbols) in the timedomain. For each numerology (e.g. subcarrier spacing) and carrier, aresource grid of Nsize,ugrid,x*NRBsc subcarriers and Nsubframe,usymbOFDM symbols is defined, starting at common resource block (CRB)Nstart,ugrid indicated by higher-layer signaling (e.g. radio resourcecontrol (RRC) signaling), where Nsize,ugrid,x is the number of resourceblocks (RBs) in the resource grid and the subscript x is DL for downlinkand UL for uplink. NRBsc is the number of subcarriers per RB. In the3GPP based wireless communication system, NRBsc is 12 generally. Thereis one resource grid for a given antenna port p, subcarrier spacingconfiguration u, and transmission direction (DL or UL). The carrierbandwidth Nsize,ugrid for subcarrier spacing configuration u is given bythe higher-layer parameter (e.g. RRC parameter). Each element in theresource grid for the antenna port p and the subcarrier spacingconfiguration u is referred to as a resource element (RE) and onecomplex symbol may be mapped to each RE. Each RE in the resource grid isuniquely identified by an index k in the frequency domain and an index 1representing a symbol location relative to a reference point in the timedomain. In the 3GPP based wireless communication system, an RB isdefined by 12 consecutive subcarriers in the frequency domain.

In the 3GPP NR system, RBs are classified into CRBs and physicalresource blocks (PRBs). CRBs are numbered from 0 and upwards in thefrequency domain for subcarrier spacing configuration u. The center ofsubcarrier 0 of CRB 0 for subcarrier spacing configuration u coincideswith ‘point A’ which serves as a common reference point for resourceblock grids. In the 3GPP NR system, PRBs are defined within a bandwidthpart (BWP) and numbered from 0 to NsizeBWP,i−1, where i is the number ofthe bandwidth part. The relation between the physical resource blocknPRB in the bandwidth part i and the common resource block nCRB is asfollows: nPRB=nCRB+NsizeBWP,i, where NsizeBWP,i is the common resourceblock where bandwidth part starts relative to CRB 0. The BWP includes aplurality of consecutive RBs. A carrier may include a maximum of N(e.g., 5) BWPs. A UE may be configured with one or more BWPs on a givencomponent carrier. Only one BWP among BWPs configured to the UE canactive at a time. The active BWP defines the UE's operating bandwidthwithin the cell's operating bandwidth.

In the present disclosure, the term “cell” may refer to a geographicarea to which one or more nodes provide a communication system, or referto radio resources. A “cell” of a geographic area may be understood ascoverage within which a node can provide service using a carrier and a“cell” as radio resources (e.g. time-frequency resources) is associatedwith bandwidth (BW) which is a frequency range configured by thecarrier. The “cell” associated with the radio resources is defined by acombination of downlink resources and uplink resources, for example, acombination of a downlink (DL) component carrier (CC) and a uplink (UL)CC. The cell may be configured by downlink resources only, or may beconfigured by downlink resources and uplink resources. Since DLcoverage, which is a range within which the node is capable oftransmitting a valid signal, and UL coverage, which is a range withinwhich the node is capable of receiving the valid signal from the UE,depends upon a carrier carrying the signal, the coverage of the node maybe associated with coverage of the “cell” of radio resources used by thenode. Accordingly, the term “cell” may be used to represent servicecoverage of the node sometimes, radio resources at other times, or arange that signals using the radio resources can reach with validstrength at other times.

In carrier aggregation (CA), two or more CCs are aggregated. A UE maysimultaneously receive or transmit on one or multiple CCs depending onits capabilities. CA is supported for both contiguous and non-contiguousCCs. When CA is configured the UE only has one radio resource control(RRC) connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell provides thenon-access stratum (NAS) mobility information, and at RRC connectionre-establishment/handover, one serving cell provides the security input.This cell is referred to as the Primary Cell (PCell). The PCell is acell, operating on the primary frequency, in which the UE eitherperforms the initial connection establishment procedure or initiates theconnection re-establishment procedure. Depending on UE capabilities,Secondary Cells (SCells) can be configured to form together with thePCell a set of serving cells. An SCell is a cell providing additionalradio resources on top of Special Cell. The configured set of servingcells for a UE therefore always consists of one PCell and one or moreSCells. For dual connectivity operation, the term Special Cell (SpCell)refers to the PCell of the master cell group (MCG) or the PSCell of thesecondary cell group (SCG). An SpCell supports PUCCH transmission andcontention-based random access, and is always activated. The MCG is agroup of serving cells associated with a master node, comprising of theSpCell (PCell) and optionally one or more SCells. The SCG is the subsetof serving cells associated with a secondary node, comprising of thePSCell and zero or more SCells, for a UE configured with dualconnectivity (DC). For a UE in RRC_CONNECTED not configured with CA/DCthere is only one serving cell comprising of the PCell. For a UE inRRC_CONNECTED configured with CA/DC the term “serving cells” is used todenote the set of cells comprising of the SpCell(s) and all SCells. InDC, two MAC entities are configured in a UE: one for the MCG and one forthe SCG.

FIG. 8 illustrates a data flow example in the 3GPP NR system.

In FIG. 8 , “RB” denotes a radio bearer, and “H” denotes a header. Radiobearers are categorized into two groups: data radio bearers (DRB) foruser plane data and signalling radio bearers (SRB) for control planedata. The MAC PDU is transmitted/received using radio resources throughthe PHY layer to/from an external device. The MAC PDU arrives to the PHYlayer in the form of a transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH aremapped to their physical channels PUSCH and PRACH, respectively, and thedownlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH,PBCH and PDSCH, respectively. In the PHY layer, uplink controlinformation (UCI) is mapped to PUCCH, and downlink control information(DCI) is mapped to PDCCH. A MAC PDU related to UL-SCH is transmitted bya UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCHis transmitted by a BS via a PDSCH based on a DL assignment.

Data unit(s) (e.g. PDCP SDU, PDCP PDU, RLC SDU, RLC PDU, RLC SDU, MACSDU, MAC CE, MAC PDU) in the present disclosure is(are)transmitted/received on a physical channel (e.g. PDSCH, PUSCH) based onresource allocation (e.g. UL grant, DL assignment). In the presentdisclosure, uplink resource allocation is also referred to as uplinkgrant, and downlink resource allocation is also referred to as downlinkassignment. The resource allocation includes time domain resourceallocation and frequency domain resource allocation. In the presentdisclosure, an uplink grant is either received by the UE dynamically onPDCCH, in a Random Access Response, or configured to the UEsemi-persistently by RRC. In the present disclosure, downlink assignmentis either received by the UE dynamically on the PDCCH, or configured tothe UE semi-persistently by RRC signalling from the BS.

FIG. 9 shows an example of possible RRC states in a wirelesscommunication system to which technical features of the presentdisclosure can be applied.

Referring to FIG. 9 , there may be 3 possible RRC states in a wirelesscommunication system (i.e., RRC_IDLE, RRC_CONNECTED and/orRRC_INACTIVE).

In RRC_IDLE (or, idle mode/state), RRC context for communication betweena UE and a network may not be established in RAN, and the UE may notbelong to a specific cell. Also, in RRC_IDLE, there is no core networkconnection for the UE. Since the device remains in sleep mode in most ofthe time to reduce battery consumption, data transfer between the UE andthe network may not occur. UEs in RRC_IDLE may periodically wake-up toreceive paging messages from the network. Mobility may be handled by theUE through cell reselection. Since uplink synchronization is notmaintained, the UE may not perform uplink transmission other thantransmissions for random access (e.g., random access preambletransmission) to move to RRC_CONNECTED.

In RRC_CONNECTED (or, connected state/mode), RRC context forcommunication between a UE and a network may be established in RAN.Also, in RRC_CONNECTED, core network connection is established for theUE. Since the UE belongs to a specific cell, cell-radio networktemporary identifier (C-RNTI) for signalings between the UE and thenetwork may be configured for the UE. Data transfer between the UE andthe network may occur. Mobility may be handled by the network—that is,the UE may provide measurement report to the network, and the networkmay transmit mobility commands to the UE to perform a mobility. Uplinktime alignment may need to be established based on a random access andmaintained for data transmission.

In RRC_INACTIVE (or, inactive state/mode), RRC context for communicationbetween a UE and a network may be kept in RAN. Data transfer between theUE and the network may not occur. Since core network connection may alsobe kept for the UE, the UE may fast transit to a connected state fordata transfer. In the transition, core network signalling may not beneeded. The RRC context may be already established in the network andidle-to-active transitions can be handled in the RAN. The UE may beallowed to sleep in a similar way as in RRC_IDLE, and mobility may behandled through cell reselection without involvement of the network. TheRRC_INACTIVE may be construed as a mix of the idle state and theconnected state.

As illustrated in FIG. 9 , the UE may transit to RRC_CONNECTED fromRRC_IDLE by performing initial attach procedure or RRC connectionestablishment procedure. The UE may transit to RRC_IDLE fromRRC_CONNECTED when detach, RRC connection release (e.g., when the UEreceives RRC release message) and/or connection failure (e.g., radiolink failure (RLF)) has occurred. The UE may transit to RRC_INACTIVEfrom RRC_CONNECTED when RRC connection is suspended (e.g., when the UEreceives RRC release message including a suspend configuration), andtransit to RRC_CONNECTED from RRC_INACTIVE when RRC connection is resumeby performing RRC connection resume procedure. The UE may transit toRRC_IDLE from RRC_INACTIVE when connection failure such as RLF hasoccurred.

Hereinafter, the minimization of driving tests (MDT) is described.

The MDT is to test by operators for coverage optimization by using a UEinstead of a vehicle. The coverage may be varied according to a locationof a base station, an arrangement of a neighbor building, and a use casescenario of a user. Therefore, the operator may need to perform adriving test, which consumes a lot of cost and resources. The MDT mayrefer to a scheme of measuring the coverage by the operator using theUE.

The MDT may comprise a logged MDT and an immediate MDT. According to thelogged MDT, the UE may perform the MDT measurement to obtain a loggedmeasurement and transmit the logged measurement to a network at aparticular time point. According to the immediate MDT, the UE mayperform the MDT measurement and transmit the result of the measurementto the network when a reporting condition is satisfied. In the loggedMDT scheme, the MDT measurement may be performed in the RRC idle mode orRRC inactive mode, whereas in the immediate MDT scheme, the MDTmeasurement may be performed in the RRC connection mode.

FIG. 10 shows an example of a process for performing an MDT to whichtechnical features of the present disclosure can be applied.

Referring to FIG. 10 , in step S1001, a UE may receive a MDTconfiguration from a network. Throughout the disclosure, the MDTconfiguration may also be referred to as “logged measurementconfiguration”. The UE may be in the RRC connected mode. Even when theUE transits to the RRC idle mode or RRC inactive mode from the RRCconnected mode, the MDT configuration may be maintained, andaccordingly, the MDT measurement result may also be maintained.

The MDT configuration may include at least one of a reference time, anarea configuration, a configuration for periodic logging or aconfiguration for event-triggered logging.

The reference time may be used to indicate a reference time used whenthe UE transmits the logged measurement. The area configuration mayindicates an area in which the UE is requested to perform the logging.

The configuration for periodic logging may comprise a logging interval.

The configuration for event-triggered logging may comprise at least oneof an event type or a logging interval. The event type may indicateout-of-service (i.e., logging instruction for out-of-service), or aspecific event (e.g., event L1). If the event type indicates thespecific event, the configuration for event-triggered logging mayfurther comprise information related to the specific event, such as alogging threshold, hysteresis value and/or a time-to-trigger (TTT)value.

Upon receiving the MDT configuration, in step S1003, the UE may start avalidity timer. The validity timer may indicate a lifetime of the MDTconfiguration. That is, the validity timer may indicate a time periodduring which the MDT configuration is valid. A value of the validitytimer may be included in the MDT configuration. Such value may be calleda logging duration. When the UE receives the MDT configuration, the UEmay set the value of the validity timer as the logging duration andstart the validity timer.

In step S1005, the UE may transit to the RRC idle mode/RRC inactive modeand then log the measurement information based on the MDT configurationwhile the validity timer is running.

For example, if a periodic logging is configured (i.e., MDTconfiguration comprises a configuration for periodic logging), the UEmay log MDT measurement information (i.e., perform a logging orstore/generate logging information) at regular time intervals defined bythe logging interval in the configuration for periodic logging.

For another example, if an event-triggered logging is configured (i.e.,MDT configuration comprises a configuration for event-triggered logging)and the event type indicates out-of-service, the UE may log MDTmeasurement information at regular time intervals as defined by thelogging interval in the configuration for event-triggered logging onlywhen the UE detects an out-of-service coverage. The out-of-servicecoverage may be detected if:

-   -   the UE is not able to detect any cells for which S criteria is        fulfilled;    -   no suitable cell or no acceptable cell can be found;    -   the UE is in any cell selection state;    -   the UE is in out-of-service; or    -   if a serving cell quality (i.e., RSRP, RSRQ or SINR) is lower        than a threshold configured by the network.

For another example, if an event-triggered logging is configured (i.e.,MDT configuration comprises a configuration for event-triggered logging)and the event type indicates out-of-service, the UE may log MDTmeasurement information immediately upon transitioning from the any cellselection state to the camped normally state.

For another example, if an event-triggered logging is configured (i.e.,MDT configuration comprises a configuration for event-triggered logging)and the event type indicates an event L1, the UE may log MDT measurementinformation at regular time intervals as defined by the logging intervalin the configuration for event-triggered logging only when a conditionrelated to the event L1 is met. The condition related to the event L1may comprise a condition that a measurement result of a serving cellplus the hysteresis value is lower than the logging threshold for theTTT value. In some cases, the hysteresis value may be 0.

In the above examples, the MDT measurement information may comprise atleast one of a cell identifier, a signal quality of a cell, a signalstrength, a measurement time or a measurement location. The signalquality/signal strength may comprise reference signal received power(RSRP), reference signal received quality (RSRQ), received signal codepower (RSCP), and/or Ec/No.

In step S1007, if there are the logged MDT measurement information, theUE may send an availability of the logged measurement information to aRAN node when the UE transits from the RRC idle mode/RRC inactive modeto the RRC connection mode. The UE may send the availability of thelogged measurement information to the network when the RRC connection isestablished, re-established, or re-configured.

In step S1009, the RAN node which receives that the logged MDTmeasurement information exists from the UE may request the UE totransmit the logged MDT measurement information. The network whichlearns about the logged measurement information may transmit aninformation request (e.g., UE information request) for requesting thereporting of the logged measurement information to the UE.

In step S1001, after/upon receiving the request to report the loggedmeasurement information, the UE may transmit a logged measurement reportcomprising the logged measurement information to the RAN node. Forexample, the UE may transmit an information response (e.g., UEinformation response) including the logged measurement information tothe RAN node. The logged measurement information may comprise contentsmeasured by the UE while the MDT measurement is performed. The loggedmeasurement information may primarily be related to a wirelessenvironment.

According to various embodiments, when the validity timer expires, theUE may discard the MDT configuration and start a conservation timer. TheUE may discard the MDT configuration and stop the MDT measurement.However, the logged measurement information may still be valid andmaintained. The conservation timer may indicate a lifetime of the loggedmeasurement information. That is, the conservation timer is related to atime period during which the logged measurement information is valid.

When the conservation timer expires, the logged measurement informationmay be discarded. When a reporting request of the logged measurementinformation is received from the RAN node during when the conservationtimer is running, the UE may report the logged measurement information.

A value of the conservation timer may be fixed. For example, the valueof the conservation timer may be 48 hours. Alternatively, the value ofthe conservation timer may be included in the MDT configuration suchthat the RAN node may notify the value of the conservation timer to theUE.

When a new MDT configuration is received, the current MDT configurationmay be updated to a new MDT configuration and the validity timer may berestarted. Also, the MDT measurement information previously loggedaccording to the previous MDT configuration may be discarded.

In the above, “any cell selection state” is a state in which a UE doesnot camp on an acceptable cell or a suitable cell. “camped normallystate” is a state in which a UE camps on a suitable cell.

The acceptable cell is a cell on which the UE may camp to obtain limitedservice (originate emergency calls and receive ETWS and CMASnotifications). Such a cell shall not barred and shall fulfil the cellselection criteria (i.e., S criteria) which is the minimum set ofrequirements to initiate an emergency call and to receive ETWS and CMASnotification in a network.

For UE not operating in SNPN Access Mode, a cell may be considered as asuitable cell if the following conditions are fulfilled:

-   -   The cell is part of either the selected PLMN or the registered        PLMN or PLMN of the Equivalent PLMN list, and for that PLMN        either:    -   The PLMN-ID of that PLMN is broadcast by the cell with no        associated CAG-IDs and CAG-only indication in the UE for that        PLMN is absent or false;    -   Allowed CAG list in the UE for that PLMN includes a CAG-ID        broadcast by the cell for that PLMN;    -   The cell selection criteria are fulfilled.

According to the latest information provided by NAS:

-   -   The cell is not barred;    -   The cell is part of at least one TA that is not part of the list        of “Forbidden Tracking Areas for Roaming”, which belongs to a        PLMN that fulfils the first bullet above.

For UE operating in SNPN Access Mode, a cell is considered as suitableif the following conditions are fulfilled:

-   -   The cell is part of either the selected SNPN or the registered        SNPN of the UE;    -   The cell selection criteria are fulfilled;

According to the latest information provided by NAS:

-   -   The cell is not barred;    -   The cell is part of at least one TA that is not part of the list        of “Forbidden Tracking Areas” which belongs to either the        selected SNPN or the registered SNPN of the UE.

The any cell selection state is applicable for RRC_IDLE and RRC_INACTIVEstate. In the any cell selection state, the UE shall perform cellselection process to find a suitable cell. If the cell selection processfails to find a suitable cell after a complete scan of all RATs and allfrequency bands supported by the UE, the UE not in SNPN AM shall attemptto find an acceptable cell of any PLMN to camp on, trying all RATs thatare supported by the UE and searching first for a high-quality cell. TheUE, which is not camped on any cell, shall stay in the any cellselection state.

The camped normally state is applicable for RRC_IDLE and RRC_INACTIVEstate.

When camped normally, the UE shall perform the following tasks:

-   -   monitor the paging channel of the cell according to information        broadcast in SIB1;    -   monitor Short Messages transmitted with P-RNTI over DCI;    -   monitor relevant System Information;    -   perform necessary measurements for the cell reselection        evaluation procedure;    -   execute the cell reselection evaluation process on the following        occasions/triggers:

1) UE internal triggers, so as to meet the specific performance;

2) When information on the BCCH used for the cell reselection evaluationprocedure has been modified.

The cell selection criterion S (or, S criterion/criteria) is fulfilledwhen Srxlev>0 and Squal>0, whereSrxlev=Q_(rxlevmeas)−(Q_(rxlevmin)+Q_(rxlevminoffset))−P_(compensation)−Qoffset_(temp)and Squal=Q_(qualmeas)−(Q_(qualmin)+Q_(qualminoffset))−Qoffset_(temp).Table 5 illustrates a definition of each parameter:

TABLE 5 Srxlev Cell selection RX level value (dB) Squal Cell selectionquality value (dB) Qoffset_(temp) Offset temporarily applied to a cellQ_(rxlevmeas) Measured cell RX level value (RSRP) Q_(qualmeas) Measuredcell quality value (RSRQ) Q_(rxlevmin) Minimum required RX level in thecell (dBm). If the UE supports SUL frequency for this cell, Q_(rxlevmin)is obtained from q-RxLevMinSUL, if present, in SIB1, SIB2 and SIB4,additionally, if Q_(rxlevminoffsetcellSUL) is present in SIB3 and SIB4for the concerned cell, this cell specific offset is added to thecorresponding Qrxlevmin to achieve the required minimum RX level in theconcerned cell; else Q_(rxlevmin) is obtained from q-RxLevMin in SIB1,SIB2 and SIB4, additionally, if Q_(rxlevminoffsetcell) is present inSIB3 and SIB4 for the concerned cell, this cell specific offset is addedto the corresponding Qrxlevmin to achieve the required minimum RX levelin the concerned cell. Q_(qualmin) Minimum required quality level in thecell (dB). Additionally, if Q_(qualminoffsetcell) is signalled for theconcerned cell, this cell specific offset is added to achieve therequired minimum quality level in the concerned cell. Q_(rxlevminoffset)Offset to the signalled Q_(rxlevmin) taken into account in the Srxlevevaluation as a result of a periodic search for a higher priority PLMNwhile camped normally in a VPLMN. Q_(qualminoffset) Offset to thesignalled Q_(qualmin) taken into account in the Squal evaluation as aresult of a periodic search for a higher priority PLMN while campednormally in a VPLMN. P_(compensation) For FR1, if the UE supports theadditionalPmax in the NR- NS-PmaxList, if present, in SIB1, SIB2 andSIB4:  max(P_(EMAX1) − P_(PowerClass), 0) − (min(P_(EMAX2),P_(PowerClass)) − min(P_(EMAX1), P_(PowerClass))) (dB);  else: max(P_(EMAX1) − P_(PowerClass), 0) (dB) For FR2, P_(compensation) isset to 0. P_(EMAX1), P_(EMAX2) Maximum TX power level of a UE may usewhen transmitting on the uplink in the cell (dBm). If UE supports SULfrequency for this cell, P_(EMAX1) and P_(EMAX2) are obtained from thep-Max for SUL in SIB1 and NR-NS- PmaxList for SUL respectively in SIB1,SIB2 and SIB4, else P_(EMAX1) and P_(EMAX2) are obtained from the p-Maxand NR-NS-PmaxList respectively in SIB1, SIB2 and SIB4 for normal UL.P_(PowerClass) Maximum RF output power of the UE (dBm) according to theUE power class.

The signalled values Q_(rxlevminoffset) rxlevminoffset andQ_(qualminoffset) are only applied when a cell is evaluated for cellselection as a result of a periodic search for a higher priority PLMNwhile camped normally in a VPLMN. During this periodic search for higherpriority PLMN, the UE may check the S criteria of a cell using parametervalues stored from a different cell of this higher priority PLMN.

Hereinafter, contents related to a multi-universal subscriber identitymodule (MUSIM) is described.

Multi-USIM devices (e.g., MUSIM device 1110) have been more and morepopular in different countries. The user may have both a personal and abusiness subscription in one device or have two personal subscriptionsin one device for different services.

FIG. 11 shows an example of a wireless environment in which a MUSIMdevice operates according to an embodiment of the present disclosure.

Referring to FIG. 11 , MUSIM device 1110 (or, MUSIM UE 1110) may have aplurality of universal subscriber identity modules (USIMs)—USIM1 1111and USIM2 1113. The MUSIM device 1110 may register to a network 1 1120based on subscription information in the USIM1 1111 to obtain aconnection A 1125 between the network 1 1120 and the MUSIM device 1110.The MSUIM device 1110 may also register to a network 2 1130 based onsubscription information in the USIM2 1113 to obtain a connection B 1135between the network 2 1130 and the MUSIM device 1110. The MUSIM device1110 may use the USIM1 1111 to perform a communication with the network1 1120 over the connection A 1125, and use the USIM2 1113 to perform acommunication with the network 2 1130 over the connection B 1135.

In a wireless environment in which a MUSIM device operates, thefollowing properties may hold:

-   -   Each registration from the USIMS of a MUSIM device may be        handled independently.    -   Each registered USIM in the MUSIM device may be associated with        a dedicated international mobile equipment identity        (IMEI)/permanent equipment identifier (PEI).    -   A MUSIM UE may be connected with i) evolved packet system (EPS)        on one USIM and 5G system (5GS) on the other USIM; ii) EPS on        both USIMs; or iii) 5GS on both USIMs.    -   A MUSIM UE may be a single reception (RX)/dual RX/single        transmission (TX)/Dual TX UE. Single RX may allow the MUSIM UE        to receive traffic from only one network at one time. Dual RX        may allow the MUSIM UE to simultaneously receive traffic from        two networks. Single TX may allow the MUSIM UE to transmit        traffic to one network at one time. Dual TX may allow the MUSIM        UE to simultaneously transmit traffic to two networks. The terms        single RX/TX and Dual RX/TX do not refer to a device type. A        single UE may, as an example, use Dual TX in some cases but        Single TX in other case.    -   If/when the multiple USIMs in the MUSIM device are served by        different serving networks, network coordination between the        serving networks may not be required.    -   A MUSIM device with different USIMs may be camping with all        USIMs on the same serving network RAN node, or the MUSIM device        may be camping on different serving networks RAN nodes.    -   USIMs may belong to same or different operators. Coordination        between involved operators may not be required.    -   USIM may be a physical SIM or embedded SIM (eSIM).

While actively communicating with a first system/network, a MUSIM UE mayneed to periodically monitor a second system/network (e.g. tosynchronize, read the paging channel, perform measurements, or read thesystem information). The periodical activity on the second system may ormay not have performance impact on the first system the UE iscommunicating with, depending on the UE implementation (i.e., singlereception (Rx) or dual Rx).

In some cases, the UE equipped with different USIMs may have pagingcollisions which results in missed paging. When the UE receives a pagein the second system while actively communicating with the first system,the UE may need to decide whether the UE should respond to this pagingor not. When the UE decides to respond to the paging in the secondsystem, the UE may need to stop the current activity in the firstsystem. For example, the first system may suspend or release the ongoingconnection with the UE.

Meanwhile, a MUSIM UE may have concurrent registrations associated withseveral USIMs. While actively communicating with the system associatedwith a first USIM (e.g., current system, first system and/or firstnetwork), the MUSIM UE may determine that the MUSIM UE needs to performsome activity (e.g. respond to a paging, or perform mobility update) inthe other system associated with a second USIM(s) (e.g., second systemand/or second network).

While the MUSIM UE is communicating with the second network based on thesecond SIM, information for notifying that the MUSIM UE has been enteredan out-of-service coverage may be absent. The network is only able toconfigure event-based logging/event-triggered logging for detecting theout-of-service coverage without considering the MUSIM operation. Thatis, the MUSIM UE can just log the out-of-service coverage if theout-of-service coverage is detected on the first system/network afterswitching the MUSIM operation from the second system/network to thefirst system/network. However, in fact, the MUSIM UE may have enteredthe out-of-service coverage while the MUSIM UE is communicating with thesecond system/network, i.e., before actually switching the MUSIMoperation from the second system/network to the first system/network.Then, the MUSIM UE cannot indicate information that the MUSIM UE hadentered the out-of-service coverage before switching the MUSIM operationfrom the second system/network to the first system/network. Due to lackof this information, the network, i.e. the first system/network, justinterprets the logging information for the out-of-service coverage whichmay be wrong to the actual size/area of the out-of-service coverage.

Therefore, according to various embodiments of the present disclosure,while performing MUSIM operation, the UE may store (and/or log) loggedmeasurement information with out-of-service coverage information if thenetwork indicates the UE to acquire the out-of-service coverageinformation for logged measurement and the UE detects that the UE is inthe out-of-service coverage. The UE may additionally set a newindication in the out-of-service coverage information indicating thatthe UE may have entered the out-of-service coverage in the secondnetwork before the UE detects the out-of-service coverage as soon asswitching the MUSIM operation from the first network to the secondnetwork.

FIG. 12 shows an example of a method performed by a wireless deviceaccording to an embodiment of the present disclosure. Steps illustratedin FIG. 12 may also be performed by a UE.

Referring to FIG. 12 , in step S1201, the wireless device may registerto a first network and a second network.

In step S1203, the wireless device may receive a logging instruction forout-of-service. For example, the wireless device may receive a logginginstruction for out-of-service from the first network.

In step S1205, the wireless device may detect an out-of-service coverageupon switching to the first network from the second network. Forexample, the wireless device may detect the out-of-service coveragewhile the wireless device operates on the first network.

In step S1207, the wireless device may generate logging information forthe detected out-of-service coverage based on the logging instructionfor out-of-service. The logging information may comprise informationinforming that the out-of-service coverage is detected upon switching tothe first network from the second network.

In step S1209, the wireless device may transmit the logging information.The wireless device may transmit the logging information to at least oneof the first network or the second network.

According to various embodiments, the wireless device may be equippedwith multiple universal subscriber identity modules (MUSIM) including afirst USIM related to the first network and a second USIM related to thesecond. The wireless device may register to the first network based onthe first USIM. The wireless device may register to the second networkbased on the second USIM.

According to various embodiments, the wireless device may perform anoperation on the first network. The wireless device may receive a pagingfrom the second network while performing the operation on the firstnetwork. Upon receiving the paging from the second network, the wirelessdevice may establish a connection with the second network. The wirelessdevice may perform an operation on the second network based on theconnection with the second network.

According to various embodiments, the operation on the first network maycomprise at least one of a connected mode operation, an inactive modeoperation or an idle mode operation performed on the first network basedon the first SIM. The operation on the second network may comprise atleast one of a connected mode operation, an inactive mode operation oran idle mode operation performed on the second network based on thesecond SIM.

According to various embodiments, the wireless device may perform alogging of measurement information on the first network while performingthe operation on the second network. The wireless device may transmit,to the second network, the logged measurement information on the firstnetwork.

According to various embodiments, to switch to the first network fromthe second network, the wireless device may release the connection withthe second network after the operation on the second network iscompleted. The wireless device may perform an operation on the firstnetwork after releasing the connection with the second network.

According to various embodiments, the logging instruction forout-of-service may instruct the wireless device to generate the logginginformation when detecting the out-of-service coverage.

According to various embodiments, the wireless device may detect theout-of-service coverage if/when:

-   -   the wireless device is not able to detect any cells for which        cell selection criteria is fulfilled;    -   no suitable cell or no acceptable cell is found;    -   the wireless device is in any cell selection state; or    -   a serving cell quality is lower than a threshold configured by a        network.

According to various embodiments, the wireless device may receive aconfiguration for event-triggered logging comprising a logging intervaland the logging instruction for out-of-service. The wireless device maygenerate, based on the logging instruction for out-of-service, thelogging information at regular time intervals determined by the logginginterval when detecting the out-of-service coverage.

According to various embodiments, to generate the logging informationfor the detected out-of-service coverage, the wireless device may logmeasurement information when detecting the out-of-service coverage,based on the logging instruction for out-of-service. The loggedmeasurement information may correspond to the logging information.

According to various embodiments, the logging information may compriseat least one of a cell identifier, a signal quality of a cell, ameasurement time or a measurement location.

According to various embodiments, the information informing that theout-of-service coverage is detected upon switching to the first networkfrom the second network may comprise information informing that thewireless device has entered the out-of-service coverage while performinga communication with the second network.

According to various embodiments, the logging information for thedetected out-of-service coverage may be used to identify an area or sizeof the out-of-service coverage.

According to various embodiments, the wireless device may register toboth a first network and a second network. The wireless device mayreceive a logged measurement configuration including an event-basedlogging information to detect out-of-service coverage (i.e., logginginstruction for out-of-service) from the first network. The wirelessdevice may switch an operation from the first network to the secondnetwork. The wireless device may detect out-of-service coverage uponswitching the operation back to the first network from the secondnetwork. The wireless device may log out-of-service coverage informationbased on the event-based logging information. The out-of-servicecoverage information may include an indication that the wireless devicehas entered the out-of-service coverage while performing the operationwith the second network. The wireless device may report logginginformation including the out-of-service coverage information afterestablishing a connection with the first network.

FIG. 13 shows an example of a method performed by a base station (BS) ina first network according to an embodiment of the present disclosure.

Referring to FIG. 13 , in step S1301, the BS may perform at least partof a procedure for registering a wireless device to the first networkand a second network.

In step S1303, the BS may transmit, to the wireless device, a logginginstruction for out-of-service.

In step S1305, the BS may receive, from the wireless device, logginginformation for an out-of-service coverage which is generated based onthe logging instruction for out-of-coverage. The logging information maycomprise information informing that the out-of-service coverage isdetected upon the wireless device switching to the first network fromthe second network.

In step S1307, the BS may identify an area of the out-of-servicecoverage based on the logging information.

The BS in FIG. 13 may be an example of a second device 220 in FIG. 2 ,and therefore, steps of the BS as illustrated in FIG. 13 may beimplemented by the second device 220. For example, the processor 221 maybe configured to perform at least part of a procedure for registering awireless device to the first network and a second network. The processor221 may be configured to control the transceiver 223 to transmit, to thewireless device, a logging instruction for out-of-service. The processor221 may be configured to control the transceiver 223 to receive, fromthe wireless device, logging information for an out-of-service coveragewhich is generated based on the logging instruction for out-of-coverage.The logging information may comprise information informing that theout-of-service coverage is detected upon the wireless device switchingto the first network from the second network. The processor 221 may beconfigured to identify an area of the out-of-service coverage based onthe logging information.

FIG. 14 shows an example of a method for logging out-of-service coverageinformation during MUSIM operation according to an embodiment of thepresent disclosure. Steps illustrated in FIG. 14 may be performed by awireless device and/or a UE.

Referring to FIG. 14 , in step S1401, the UE may initiate/perform an RRCconnection establishment procedure with a network on SIM_A (i.e.,network A). The UE may be in a non-connected mode for a network on SIM_B(i.e., network B).

The UE may be capable to support MUSIM operation. The MUSIM operationmay comprise at least one of an operation on network A or an operationon network B. The operation on network A may comprise a connected modeoperation/inactive mode operation/idle mode operation performed on thenetwork A based on the SIM_A. The operation on network B may comprise aconnected mode operation/inactive mode operation/idle mode operationperformed on the network B based on the SIM_B.

The UE may be capable to support logging of measurement information inRRC_IDLE/RRC_INACTIVE. The UE may initiate the RRC connectionestablishment procedure to the network A.

In step S1403, the UE may release the RRC connection from the network A.Therefore, the UE may be in a non-connected mode for the network A andthe network B.

The UE may receive an RRC release message from the network A. The UE mayenter RRC_IDLE or RRC_INACTIVE state in the network A. The UE may beconfigured with the logged measurement configuration with event-basedout-of-service coverage information (i.e., logged measurementconfiguration including a configuration for event-triggered logging withevent type set to out-of-service) by the network A. The loggedmeasurement configuration may be provided by a dedicated RRC signallingfrom the network A after the RRC connection establishment, e.g., via RRCRelease message or LoggedMeasurementConfiguration message. The loggedmeasurement configuration may include at least one of logging period,logging interval, logging objectives (e.g. frequencies or cells), and/orout-of-service logging indication (i.e., logging instruction forout-of-service). The out-of-service logging indication may be forevent-based logging and may indicate the UE to log measurementinformation of the logging objectives when the UE enters theout-of-service coverage. That is, the UE may perform logging ofmeasurement information as soon as the out-of-service coverage isdetected. The out-of-service coverage may be detected by the UE when atleast one of the following conditions is satisfied:

-   -   If UE is not able to detect any cells for which S criteria is        fulfilled;    -   If no suitable or acceptable cell can be found;    -   If UE is in any cell selection state;    -   If UE is in out-of-service; or    -   If serving cell quality, i.e. RSRP, RSRQ, or SINR, is lower than        a threshold configured by the network.

In step S1405, the UE may receive a paging from the network B. The UEmay be in a non-connected mode for the network A and the network B.

While performing MUSIM operation, the UE may monitor paging informationfrom the network B. While monitoring paging information on the networkB, the UE may receive a paging message from the network B.

In step S1407, the UE may initiate/perform an RRC connectionestablishment procedure with the network B. The UE may be in anon-connected mode for the network A.

Upon reception of the paging message from the network B, the UE mayswitch SIM operation for the paging message from the network A to thenetwork B, i.e. establishing RRC connection with the network B.

Whenever the UE needs to perform logged measurement on the network Aaccording to the logged measurement configuration, the UE may performlogged measurement on the network A while performing MUSIM operation onthe network B. To avoid conflict operation between logged measurement onthe network A and MUSIM operation on the network B, the UE may reportlogged measurement information of other SIM (i.e., SIM A) to the networkB via RRC signalling. The UE may firstly indicate to the network B thatthere is any logged measurement information of other SIM. Then, afterreception of a request for logged measurement information of other SIMfrom the network B, the UE may report the logged measurement informationof other SIM to the network B via RRC dedicated message. Otherwise, theUE may simply report the logged measurement information of other SIM tothe network B via RRC dedicated message without the request from thenetwork B. After reception of the logged measurement information ofother SIM, the network B may change data scheduling between the UE andthe network B considering the logged measurement information of thenetwork A.

In step S1409, the UE may revert back to the network A for which the UEis currently in a non-connected mode.

After communicating with the network B, the UE may receive an RRCrelease from the network B. Upon reception of the RRC release messagefrom the network B, the UE may release the RRC connection with thenetwork B. After RRC connection release on the network B, the UE mayswitch SIM operation from the network B to the network A if theoperation on the network A is still higher prioritized than theoperation on the network B.

In step S1411, the UE may detect an out-of-service coverage whenreturning back to the network A. The UE may be in a non-connected modefor the network A and the network B.

After switching SIM operation from the network B to the network A, theUE may detect an out-of-service coverage. Then, the UE may perform theevent-based logging for the out-of-coverage. When logging theout-of-service coverage information (i.e., measurement information forthe detected out-of-service coverage), the UE may set additionalinformation with the legacy out-of-service information, e.g.,relativeTimeStamp, locationInfo, anyCellSelectionDetected to indicatethe detection of no suitable or no acceptable cell found,servCellIdentity to indicate global cell identity of the last loggedcell that the UE was camping on, measResultServCell to include thequantities of the last logged cell the UE was camping on. The additionalinformation may indicate that the out-of-service coverage has beendetected as soon as switching back to the network A and the UE may be inout-of-service coverage in the network A while performing MUSIMoperation on the network B (i.e., before switching back to the networkA). The additional information can be a single indication.

In step S1413, the UE may report the logged measurement information tothe network A after establishing an RRC connection with the network A.The UE may be in a connected mode for the network A, and non-connectedmode for the network B.

After establishing an RRC connection with the network A, the UE mayconstruct the logged measurement report including the stored loggedmeasurement entries for the out-of-service coverage. The UE may indicateto the network that the logged measurement report is available. Theindication may be included in RRCSetupComplete message. The UE maytransmit the logged measurement report to the network. The transmissionof the logged measurement report may be performed upon request (e.g.,UEInformationRequest) by the network, e.g., via theUEInformationResponse message.

FIG. 15 shows a UE to implement an embodiment of the present disclosure.The present disclosure described above for UE side may be applied tothis embodiment. The UE in FIG. 15 may be an example of first device 210as illustrated in FIG. 2 .

A UE includes a processor 1510 (i.e., processor 211), a power managementmodule 1511, a battery 1512, a display 1513, a keypad 1514, a subscriberidentification module (SIM) card 1515, a memory 1520 (i.e., memory 212),a transceiver 1530 (i.e., transceiver 213), one or more antennas 1531, aspeaker 1540, and a microphone 1541.

The processor 1510 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 1510. Theprocessor 1510 may include application-specific integrated circuit(ASIC), other chipset, logic circuit and/or data processing device. Theprocessor 1510 may be an application processor (AP). The processor 1510may include at least one of a digital signal processor (DSP), a centralprocessing unit (CPU), a graphics processing unit (GPU), a modem(modulator and demodulator). An example of the processor 1510 may befound in SNAPDRAGON™ series of processors made by Qualcomm®, EXYNOS™series of processors made by Samsung®, A series of processors made byApple®, HELIO™ series of processors made by MediaTek®, ATOM™ series ofprocessors made by Intel® or a corresponding next generation processor.

The processor 1510 may be configured to, or configured to control thetransceiver 1530 to implement steps performed by the UE and/or thewireless device throughout the disclosure.

The power management module 1511 manages power for the processor 1510and/or the transceiver 1530. The battery 1512 supplies power to thepower management module 1511. The display 1513 outputs results processedby the processor 1510. The keypad 1514 receives inputs to be used by theprocessor 1510. The keypad 1514 may be shown on the display 1513. TheSIM card 1515 is an integrated circuit that is intended to securelystore the international mobile subscriber identity (IMSI) number and itsrelated key, which are used to identify and authenticate subscribers onmobile telephony devices (such as mobile phones and computers). It isalso possible to store contact information on many SIM cards.

The memory 1520 is operatively coupled with the processor 1510 andstores a variety of information to operate the processor 1510. Thememory 1520 may include read-only memory (ROM), random access memory(RAM), flash memory, memory card, storage medium and/or other storagedevice. When the embodiments are implemented in software, the techniquesdescribed herein can be implemented with modules (e.g., procedures,functions, and so on) that perform the functions described herein. Themodules can be stored in the memory 1520 and executed by the processor1510. The memory 1520 can be implemented within the processor 1510 orexternal to the processor 1510 in which case those can becommunicatively coupled to the processor 1510 via various means as isknown in the art.

The transceiver 1530 is operatively coupled with the processor 1510, andtransmits and/or receives a radio signal. The transceiver 1530 includesa transmitter and a receiver. The transceiver 1530 may include basebandcircuitry to process radio frequency signals. The transceiver 1530controls the one or more antennas 1531 to transmit and/or receive aradio signal.

The speaker 1540 outputs sound-related results processed by theprocessor 1510. The microphone 1541 receives sound-related inputs to beused by the processor 1510.

According to various embodiments, the processor 1510 may be configuredto, or configured to control the transceiver 1530 to implement stepsperformed by the UE and/or the wireless device throughout thedisclosure. For example, the processor 1510 may be configured toregister to a first network and a second network. The processor 1510 maybe configured to control the transceiver 1530 to receive a logginginstruction for out-of-service. The processor 1510 may be configured todetect an out-of-service coverage upon switching to the first networkfrom the second network. The processor 1510 may be configured togenerate logging information for the detected out-of-service coveragebased on the logging instruction for out-of-service. The logginginformation may comprise information informing that the out-of-servicecoverage is detected upon switching to the first network from the secondnetwork. The processor 1510 may be configured to control the transceiver1530 to transmit the logging information.

FIG. 16 shows another example of a wireless communication system towhich the technical features of the present disclosure can be applied.

Referring to FIG. 16 , the wireless communication system may include afirst device 1610 (i.e., first device 210) and a second device 1620(i.e., second device 220).

The first device 1610 may include at least one transceiver, such as atransceiver 1611, and at least one processing chip, such as a processingchip 1612. The processing chip 1612 may include at least one processor,such a processor 1613, and at least one memory, such as a memory 1614.The memory may be operably connectable to the processor 1613. The memory1614 may store various types of information and/or instructions. Thememory 1614 may store a software code 1615 which implements instructionsthat, when executed by the processor 1613, perform operations of thefirst device 910 described throughout the disclosure. For example, thesoftware code 1615 may implement instructions that, when executed by theprocessor 1613, perform the functions, procedures, and/or methods of thefirst device 1610 described throughout the disclosure. For example, thesoftware code 1615 may control the processor 1613 to perform one or moreprotocols. For example, the software code 1615 may control the processor1613 to perform one or more layers of the radio interface protocol.

The second device 1620 may include at least one transceiver, such as atransceiver 1621, and at least one processing chip, such as a processingchip 1622. The processing chip 1622 may include at least one processor,such a processor 1623, and at least one memory, such as a memory 1624.The memory may be operably connectable to the processor 1623. The memory1624 may store various types of information and/or instructions. Thememory 1624 may store a software code 1625 which implements instructionsthat, when executed by the processor 1623, perform operations of thesecond device 1620 described throughout the disclosure. For example, thesoftware code 1625 may implement instructions that, when executed by theprocessor 1623, perform the functions, procedures, and/or methods of thesecond device 1620 described throughout the disclosure. For example, thesoftware code 1625 may control the processor 1623 to perform one or moreprotocols. For example, the software code 1625 may control the processor1623 to perform one or more layers of the radio interface protocol.

According to various embodiments, the first device 1610 as illustratedin FIG. 16 may comprise a wireless device. The wireless device maycomprise a transceiver 1611, a processing chip 1612. The processing chip1612 may comprise a processor 1613, and a memory 1614. The memory 1614may be operably connectable to the processor 1613. The memory 1614 maystore various types of information and/or instructions. The memory 1614may store a software code 1615 which implements instructions that, whenexecuted by the processor 1613, perform operations comprising:registering to a first network and a second network; receiving a logginginstruction for out-of-service; detecting an out-of-service coverageupon switching to the first network from the second network; generatinglogging information for the detected out-of-service coverage based onthe logging instruction for out-of-service, wherein the logginginformation comprises information informing that the out-of-servicecoverage is detected upon switching to the first network from the secondnetwork; and transmitting the logging information.

According to various embodiments, a non-transitory computer-readablemedium may have stored thereon a plurality of instructions. Theplurality of instructions, when executed by a processor of a wirelessdevice, may cause the wireless device to: register to a first networkand a second network; receive a logging instruction for out-of-service;detect an out-of-service coverage upon switching to the first networkfrom the second network; generate logging information for the detectedout-of-service coverage based on the logging instruction forout-of-service, wherein the logging information comprises informationinforming that the out-of-service coverage is detected upon switching tothe first network from the second network; and transmit the logginginformation.

The present disclosure may be applied to various future technologies,such as AI, robots, autonomous-driving/self-driving vehicles, and/orextended reality (XR).

<AI>

AI refers to artificial intelligence and/or the field of studyingmethodology for making it. Machine learning is a field of studyingmethodologies that define and solve various problems dealt with in AI.Machine learning may be defined as an algorithm that enhances theperformance of a task through a steady experience with any task.

An artificial neural network (ANN) is a model used in machine learning.It can mean a whole model of problem-solving ability, consisting ofartificial neurons (nodes) that form a network of synapses. An ANN canbe defined by a connection pattern between neurons in different layers,a learning process for updating model parameters, and/or an activationfunction for generating an output value. An ANN may include an inputlayer, an output layer, and optionally one or more hidden layers. Eachlayer may contain one or more neurons, and an ANN may include a synapsethat links neurons to neurons. In an ANN, each neuron can output asummation of the activation function for input signals, weights, anddeflections input through the synapse. Model parameters are parametersdetermined through learning, including deflection of neurons and/orweights of synaptic connections. The hyper-parameter means a parameterto be set in the machine learning algorithm before learning, andincludes a learning rate, a repetition number, a mini batch size, aninitialization function, etc. The objective of the ANN learning can beseen as determining the model parameters that minimize the lossfunction. The loss function can be used as an index to determine optimalmodel parameters in learning process of ANN.

Machine learning can be divided into supervised learning, unsupervisedlearning, and reinforcement learning, depending on the learning method.Supervised learning is a method of learning ANN with labels given tolearning data. Labels are the answers (or result values) that ANN mustinfer when learning data is input to ANN. Unsupervised learning can meana method of learning ANN without labels given to learning data.Reinforcement learning can mean a learning method in which an agentdefined in an environment learns to select a behavior and/or sequence ofactions that maximizes cumulative compensation in each state.

Machine learning, which is implemented as a deep neural network (DNN)that includes multiple hidden layers among ANN, is also called deeplearning. Deep learning is part of machine learning. In the following,machine learning is used to mean deep learning.

FIG. 17 shows an example of an AI device to which the technical featuresof the present disclosure can be applied.

The AI device 1700 may be implemented as a stationary device or a mobiledevice, such as a TV, a projector, a mobile phone, a smartphone, adesktop computer, a notebook, a digital broadcasting terminal, a PDA, aPMP, a navigation device, a tablet PC, a wearable device, a set-top box(STB), a digital multimedia broadcasting (DMB) receiver, a radio, awashing machine, a refrigerator, a digital signage, a robot, a vehicle,etc.

Referring to FIG. 17 , the AI device 1700 may include a communicationpart 1710, an input part 1780, a learning processor 1730, a sensing part1740, an output part 1750, a memory 1760, and a processor 1770.

The communication part 1710 can transmit and/or receive data to and/orfrom external devices such as the AI devices and the AI server usingwire and/or wireless communication technology. For example, thecommunication part 1710 can transmit and/or receive sensor information,a user input, a learning model, and a control signal with externaldevices. The communication technology used by the communication part1710 may include a global system for mobile communication (GSM), a codedivision multiple access (CDMA), an LTE/LTE-A, a 5G, a WLAN, a Wi-Fi,Bluetooth™, radio frequency identification (RFID), infrared dataassociation (IrDA), ZigBee, and/or near field communication (NFC).

The input part 1780 can acquire various kinds of data. The input part1780 may include a camera for inputting a video signal, a microphone forreceiving an audio signal, and a user input part for receivinginformation from a user. A camera and/or a microphone may be treated asa sensor, and a signal obtained from a camera and/or a microphone may bereferred to as sensing data and/or sensor information. The input part1780 can acquire input data to be used when acquiring an output usinglearning data and a learning model for model learning. The input part1780 may obtain raw input data, in which case the processor 1770 or thelearning processor 1730 may extract input features by preprocessing theinput data.

The learning processor 1730 may learn a model composed of an ANN usinglearning data. The learned ANN can be referred to as a learning model.The learning model can be used to infer result values for new input datarather than learning data, and the inferred values can be used as abasis for determining which actions to perform. The learning processor1730 may perform AI processing together with the learning processor ofthe AI server. The learning processor 1730 may include a memoryintegrated and/or implemented in the AI device 1700. Alternatively, thelearning processor 1730 may be implemented using the memory 1760, anexternal memory directly coupled to the AI device 1700, and/or a memorymaintained in an external device.

The sensing part 1740 may acquire at least one of internal informationof the AI device 1700, environment information of the AI device 1700,and/or the user information using various sensors. The sensors includedin the sensing part 1740 may include a proximity sensor, an illuminancesensor, an acceleration sensor, a magnetic sensor, a gyro sensor, aninertial sensor, an RGB sensor, an IR sensor, a fingerprint recognitionsensor, an ultrasonic sensor, an optical sensor, a microphone, a lightdetection and ranging (LIDAR), and/or a radar.

The output part 1750 may generate an output related to visual, auditory,tactile, etc. The output part 1750 may include a display unit foroutputting visual information, a speaker for outputting auditoryinformation, and/or a haptic module for outputting tactile information.

The memory 1760 may store data that supports various functions of the AIdevice 1700. For example, the memory 1760 may store input data acquiredby the input part 1780, learning data, a learning model, a learninghistory, etc.

The processor 1770 may determine at least one executable operation ofthe AI device 1700 based on information determined and/or generatedusing a data analysis algorithm and/or a machine learning algorithm. Theprocessor 1770 may then control the components of the AI device 1700 toperform the determined operation. The processor 1770 may request,retrieve, receive, and/or utilize data in the learning processor 1730and/or the memory 1760, and may control the components of the AI device1700 to execute the predicted operation and/or the operation determinedto be desirable among the at least one executable operation. Theprocessor 1770 may generate a control signal for controlling theexternal device, and may transmit the generated control signal to theexternal device, when the external device needs to be linked to performthe determined operation. The processor 1770 may obtain the intentioninformation for the user input and determine the user's requirementsbased on the obtained intention information. The processor 1770 may useat least one of a speech-to-text (STT) engine for converting speechinput into a text string and/or a natural language processing (NLP)engine for acquiring intention information of a natural language, toobtain the intention information corresponding to the user input. Atleast one of the STT engine and/or the NLP engine may be configured asan ANN, at least a part of which is learned according to a machinelearning algorithm. At least one of the STT engine and/or the NLP enginemay be learned by the learning processor 1730 and/or learned by thelearning processor of the AI server, and/or learned by their distributedprocessing. The processor 1770 may collect history information includingthe operation contents of the AI device 1700 and/or the user's feedbackon the operation, etc. The processor 1770 may store the collectedhistory information in the memory 1760 and/or the learning processor1730, and/or transmit to an external device such as the AI server. Thecollected history information can be used to update the learning model.The processor 1770 may control at least some of the components of AIdevice 1700 to drive an application program stored in memory 1760.Furthermore, the processor 1770 may operate two or more of thecomponents included in the AI device 1700 in combination with each otherfor driving the application program.

FIG. 18 shows an example of an AI system to which the technical featuresof the present disclosure can be applied.

Referring to FIG. 18 , in the AI system, at least one of an AI server1820, a robot 1810 a, an autonomous vehicle 1810 b, an XR device 1810 c,a smartphone 1810 d and/or a home appliance 1810 e is connected to acloud network 1800. The robot 1810 a, the autonomous vehicle 1810 b, theXR device 1810 c, the smartphone 1810 d, and/or the home appliance 1810e to which the AI technology is applied may be referred to as AI devices1810 a to 1810 e.

The cloud network 1800 may refer to a network that forms part of a cloudcomputing infrastructure and/or resides in a cloud computinginfrastructure. The cloud network 1800 may be configured using a 3Gnetwork, a 4G or LTE network, and/or a 5G network. That is, each of thedevices 1810 a to 1810 e and 1820 consisting the AI system may beconnected to each other through the cloud network 1800. In particular,each of the devices 1810 a to 1810 e and 1820 may communicate with eachother through a base station, but may directly communicate with eachother without using a base station.

The AI server 1820 may include a server for performing AI processing anda server for performing operations on big data. The AI server 1820 isconnected to at least one or more of AI devices constituting the AIsystem, i.e. the robot 1810 a, the autonomous vehicle 1810 b, the XRdevice 1810 c, the smartphone 1810 d and/or the home appliance 1810 ethrough the cloud network 1800, and may assist at least some AIprocessing of the connected AI devices 1810 a to 1810 e. The AI server1820 can learn the ANN according to the machine learning algorithm onbehalf of the AI devices 1810 a to 1810 e, and can directly store thelearning models and/or transmit them to the AI devices 1810 a to 1810 e.The AI server 1820 may receive the input data from the AI devices 1810 ato 1810 e, infer the result value with respect to the received inputdata using the learning model, generate a response and/or a controlcommand based on the inferred result value, and transmit the generateddata to the AI devices 1810 a to 1810 e. Alternatively, the AI devices1810 a to 1810 e may directly infer a result value for the input datausing a learning model, and generate a response and/or a control commandbased on the inferred result value.

Various embodiments of the AI devices 1810 a to 1810 e to which thetechnical features of the present disclosure can be applied will bedescribed. The AI devices 1810 a to 1810 e shown in FIG. 18 can be seenas specific embodiments of the AI device 1700 shown in FIG. 17 .

The present disclosure can have various advantageous effects.

For example, when the network provides a configuration to perform alogged measurement to the UE which is capable to support MUSIMoperation, in addition to the logged measurement result, the UE canprovide an indication that the out-of-service coverage has been enteredbefore switching MUSIM operation in a logged measurement report so thatthe network can assume that the actual size/area of the out-of-servicecoverage is bigger than the reported size/area. Therefore, the networkcan prevent misinterpretation of the size/area of the out-of-servicecoverage by the indication in the logged measurement report.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope of the present disclosure.

Claims in the present description can be combined in a various way. Forinstance, technical features in method claims of the present descriptioncan be combined to be implemented or performed in an apparatus, andtechnical features in apparatus claims can be combined to be implementedor performed in a method. Further, technical features in method claim(s)and apparatus claim(s) can be combined to be implemented or performed inan apparatus. Further, technical features in method claim(s) andapparatus claim(s) can be combined to be implemented or performed in amethod. Other implementations are within the scope of the followingclaims.

What is claimed is:
 1. A method performed by a wireless device in awireless communication system, the method comprising: registering to afirst network and a second network; receiving a logging instruction forout-of-service; detecting an out-of-service coverage upon switching tothe first network from the second network; generating logginginformation for the detected out-of-service coverage based on thelogging instruction for out-of-service, wherein the logging informationcomprises information informing that the out-of-service coverage isdetected upon switching to the first network from the second network;and transmitting the logging information.
 2. The method of claim 1,wherein the wireless device is equipped with multiple universalsubscriber identity modules (MUSIM) including a first USIM related tothe first network and a second USIM related to the second network, andwherein the registering to the first network and the second networkcomprises: registering to the first network based on the first USIM; andregistering to the second network based on the second USIM.
 3. Themethod of claim 1, further comprising: performing an operation on thefirst network; receiving a paging from the second network whileperforming the operation on the first network; upon receiving the pagingfrom the second network, establishing a connection with the secondnetwork; and performing an operation on the second network based on theconnection with the second network.
 4. The method of claim 3, furthercomprising: performing a logging of measurement information on the firstnetwork while performing the operation on the second network; andtransmitting, to the second network, the logged measurement informationon the first network.
 5. The method of claim 3, wherein the switching tothe first network from the second network comprises: releasing theconnection with the second network after the operation on the secondnetwork is completed; and performing an operation on the first networkafter releasing the connection with the second network.
 6. The method ofclaim 1, wherein the logging instruction for out-of-service instructsthe wireless device to generate the logging information when detectingthe out-of-service coverage.
 7. The method of claim 1, wherein thedetecting of the out-of-service coverage comprises detecting at leastone of: a first condition that the wireless device is not able to detectany cells for which cell selection criteria is fulfilled; a secondcondition that no suitable cell or no acceptable cell is found; a thirdcondition that the wireless device is in any cell selection state; or afourth condition that a serving cell quality is lower than a thresholdconfigured by a network.
 8. The method of claim 1, further comprising:receiving a configuration for event-triggered logging comprising alogging interval and the logging instruction for out-of-service, whereinthe generating of the logging information for the detectedout-of-service coverage comprises: generating, based on the logginginstruction for out-of-service, the logging information at regular timeintervals determined by the logging interval when detecting theout-of-service coverage.
 9. The method of claim 1, wherein thegenerating of the logging information for the detected out-of-servicecoverage comprises logging measurement information when detecting theout-of-service coverage, based on the logging instruction forout-of-service, and wherein the logged measurement informationcorresponds to the logging information.
 10. The method of claim 1,wherein the logging information comprises at least one of a cellidentifier, a signal quality of a cell, a measurement time or ameasurement location.
 11. The method of claim 1, wherein the informationinforming that the out-of-service coverage is detected upon switching tothe first network from the second network comprises informationinforming that the wireless device has entered the out-of-servicecoverage while performing a communication with the second network. 12.The method of claim 1, wherein the logging information for the detectedout-of-service coverage is used to identify an area or size of theout-of-service coverage.
 13. The method of claim 1, wherein thetransmitting of the logging information comprises transmitting thelogging information to at least one of the first network or the secondnetwork.
 14. The method of claim 1, wherein the wireless device is incommunication with at least one of a user equipment, a network, and/orautonomous vehicles other than the wireless device.
 15. A wirelessdevice in a wireless communication system comprising: a transceiver; amemory; and at least one processor operatively coupled to thetransceiver and the memory, and configured to: register to a firstnetwork and a second network; control the transceiver to receive alogging instruction for out-of-service; detect an out-of-servicecoverage upon switching to the first network from the second network;generate logging information for the detected out-of-service coveragebased on the logging instruction for out-of-service, wherein the logginginformation comprises information informing that the out-of-servicecoverage is detected upon switching to the first network from the secondnetwork; and control the transceiver to transmit the logginginformation.
 16. A non-transitory computer-readable medium having storedthereon a plurality of instructions, wherein the plurality ofinstructions, when executed by a processor of a wireless device, causethe wireless device to: register to a first network and a secondnetwork; receive a logging instruction for out-of-service; detect anout-of-service coverage upon switching to the first network from thesecond network; generate logging information for the detectedout-of-service coverage based on the logging instruction forout-of-service, wherein the logging information comprises informationinforming that the out-of-service coverage is detected upon switching tothe first network from the second network; and transmit the logginginformation.